text:
Is my understanding of a gas turbine engine compressor correct?
So I understand that the rotors add dynamic pressure to the airflow and this dynamic pressure airflow is transformed into static pressure in the stator vanes. But now does the airflow still have dynamic pressure once it leaves the stator vanes, or does it get completely transferred into static pressure?
And the static pressure stays in the airflow and keeps increasing as it goes on, it doesn't get transformed into dynamic pressure because the movement of the rotor vanes create the dynamic pressure, is that correct?

Axial compressor: "the rotor increases the absolute velocity of the fluid and the stator converts this into pressure rise"

@mins That seems odd to me. I was under the impression that the stators were there to redirect the flow, to cause the slightly orthogonal flow from the rotors into straight axial flow. The compression is from the converging shape of the chamber. Rotors accelerate the air actually into a converging chamber

If the chamber didn't converge pressure wouldn't rise, just velocity. But I'm terrible with physics

@TomMcW: Not quite. The stators pre-swirl the flow so it hits the rotors at the right angle. The rotors introduce swirl in the opposite direction, hence a new line of stators before the next rotor disc. Now the converging compressor - without the converging shape the pressure would still rise but the flow would slow down. Slower flow means less dynamic pressure, and the later rotors would have lower efficiency. Convergence is needed to keep flow speed constant and each compressor disc at top efficiency.

..the rotors add dynamic pressure to the airflow..
..this dynamic pressure airflow is transformed into static pressure in the stator vanes.

are both incorrect partially correct statements, but can be open to confusion. Dynamic pressure is transformed into static pressure continuously, by narrowing the passage through the compressor. The rotors add total pressure to the airflow, some of which is extra dynamic pressure and some extra static pressure.

The rotor vanes increase the energy contents of the gas stream. Another name for the energy contents of a gas stream is enthalpy.
Energy contents can be transformed into gas speed when allowed to expand (dynamic pressure) or into static pressure when you keep the volume confined.

For ease of reference, just take a car tyre as an example. Some little rotating implements in an air pump at the gas station provide a pressurised air stream into the tyre. Stop pumping and measure the tyre pressure: what you're measuring is static pressure. The weather news talks about high pressure and low pressure systems, that is static pressure as well. It's energy contents that has not been converted into a velocity yet, like increasing potential energy of a rock by lifting it up further.
Now get a match stick and press on the tyre valve. The air streams out of the tyre, this air stream can be called dynamic pressure. You can use the outflowing air to inflate another flat tyre, you're then converting static pressure in tyre 1 into dynamic pressure into static pressure in tyre 2. End pressure in tyre 1 is lower than when you opened the valve: total energy contents of tyre 1 is now divided over 2 tyres. No energy was added, only pumps can do that, by converting electrical energy into air pressure energy.
For the axial compressor in a jet engine:
* The rotor vanes act as the air pump, and add energy into the air stream: total pressure is increased.
* The stator vanes do nothing with the energy content of the air stream: total pressure stays the same. The swirl is removed, and some dynamic pressure is converted into static pressure.
From The Jet Engine issue 5 by Rolls Royce: notice how the total pressure rises in the rotors, and the static pressure rises as a function of the passage narrowing.

@Penguin thanks for your comments, they were helpful.

So how does the airflow have static pressure if the airflow is moving? Otherwise a pretty good explanation!

@Itzyboi Moving airflow has a static pressure as well as a dynamic pressure, and ome can comvert into the other. A stationary airflow has only static pressure. Air pressure is the average impact of air molecules, and they only stop moving at 0 deg Kelvin.

The rotors are what imparts mechanical energy to the working fluid, increasing its enthalpy.  Stators are there in order to redirect the momentum of the gas flow toward the rotor of the next compressor stage.  The gas upon exiting the stator of the last stage is going to have at least some stagnation pressure associated with its current momentum, but its more convenient to describe its energy state in terms of enthalpy.


text:
What exactly is a hot air pressure regulating valve, and what is its purpose?
Someone else has asked this question but the answer just says that it regulates the pressure of hot air, and I don't understand what that means. Does "hot air pressure" just mean "hot air"?
So I've been learning about an Airbus A320 and its air conditioning system and I'm wondering what's the point of the hot air pressure regulating valve? Why can't bleed air, which is hot compressed air, be used as hot air? Send some of the hot compressed air to the packs and some hot compressed air to the trim air valves to heat the air from the mixing unit.
Please explain what is the purpose of the hot air pressure regulating valve and even what it is. What's even the purpose if you have bleed air? Please don't tell me that the hot air pressure regulating valve regulates the pressure of hot air, I already know that. I just want to know why it is generating hot air pressure, why not just hot air? Or is hot air pressure the same thing as hot air?

"Why can't bleed air, which is hot compressed air, be used as hot air?" Because bleed air comes directly from the compressor section, at temperatures around 250°C (482°F). Turning the cabin heat on would result in 100+ passengers experiencing the face-melting scene from Indiana Jones Raiders of the Lost Ark.

The hot air pressure regulating valve does not generate hot air. The hot air is generated from the engine bleed air.
But that air does not go straight from the engines into the cabin, it would be too hot. If you want to adjust the temperature, you need a way of limiting the amount of hot air going into the cabin. That is what the regulating valve does (in conjunction with a couple of other components).

So what would happen if Hot Air regulating valve is inoperative in closed position? How does the system adjust the temperature? Does the pack control its outlet temperature?

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text:
How exactly does a pilot engage the autopilot?
I have a number of questions about auto-pilots but rather than deluge you with a long prose here let me break them down into separate questions over the next little while.
From playing around with simulators I know that the pilot has the ability to enter desired altitudes, climb rates, heading etc into the auto-pilot. However, and forgive me, whenever I see a pilot engage the auto-pilot in movies etc, it is simply a flip of the switch.
So that got me wondering how the transition is made in actuality.
Does the pilot need to enter the current altitude, heading etc before flicking the switch or does the AP take the current numbers and hold those automatically.
If it is the latter and the aircraft is in say a climbing turn when the switch is clicked.. then what? Does the aircraft continue in that pattern or what?

Depends on the aircraft/autopilot. For my aircraft, it is a three step process... First move the switch to the "TEST" position and wait for the self-test to complete. Then move it to the "ON" position. The autopilot will show "STB" or Standby. Then I can use the buttons to select a mode (ALT, HDG, APR, or NAV). The ALT will hold the current altitude, HDG will follow the heading bug (make sure to set it!), and APR/NAV will follow the localizer which can be driven by the GPS or nav radio.

Turning on the autopilot is generally a single button or switch, but with a caveat.
That big panel with the altitude selector, heading bug, nav options, etc programs the flight director, which is most likely enabled prior to even taking off and pre-programmed with your initial altitude leveloff, departure heading, etc.
While hand flying the pilot not flying who is operating the radios will update the flight director settings as your ATC instructions vary. This is generally updating altitude, heading and engaging nav.
When it is time to let Otto fly, at that point it is just a single button to slave the autopilot to the flight director.

“One Switch” to operate the Autopilot is not true. That’s just the movies.
Autopilot systems vary in each aircraft. Larger jets have it divided into two: Auto-Throttle and Auto-Pilot. Smaller aircraft/piston aircraft don’t really have auto-throttle capabilities.
The Autopilot is not just to “maintain” current flight path. It really can fly the entire flight from take-off to touchdown. This includes flying a departure procedure, en-route navigation, arrival procedure, an approach and touchdown.
Theoretically, it is possible for a pilot to not touch the aircraft controls (yoke/stick/throttle) after liftoff all the way until touchdown even if the mission is a complex IFR flight. Realistically, pilots love to fly and they will fly.
Many settings exist for each autopilot system, and these include (but are not limited to):
Lateral Navigation

Heading Mode (fly the “selected” heading”)
Nav Mode (fly the “selected” nav course)
Roll Mode

Vertical Navigation

Altitude Select Mode (Maintain the selected altitude)
Vertical Descent with a fixed speed
Vertical Descent with a fixed rate
Approch Mode (Vertical Descent with Glideslope)

Auto-Throttle

Maintain Selected Airspeed
Accelerate/Decelerate to Selected Airspeed

However, there is that master AP Switch that’ll disable all things related to the AP.

I understand that but it does not answer my question. If I am cruising at close to 9000ft do I need to rotate that altitude knob to select 9000 before I engage.. or does it grab the 9150 I'm actually at.

This is a lot about what an auto-pilot can do, but only your first sentence is applicable to the question at hand, and as Trevor says, doesn't really answer the meat of what he is getting at. @Trevor It depends, with autopilots that have a settable altitude, it must be set, other ones just hold the current altitude (and don't have knobs/displays to show it).

Understandably the answer says that auto-pilot must be configured before it can be engaged, so NO - there is more than one switch to get it active from scratch. There is the one switch to turn it off.

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text:
What is a typical altitude for a dogfight?
At what altitude(s) do dogfights typically occur? How has this changed from World War I up to now?

At what altitude(s) do dogfights typically occur?

All of them.
Throughout history dogfights have generally started at one of the aircraft's "best altitude", which depends on the aircraft, and then descended as the pilot's trade altitude for airspeed.
Altitude disparity can be so great that one or the other will simply not engage, or do so at a serious penalty if they are forced to. This occurred during the Falklands when the Argentinian aircraft had much more performance than the UK's Harriers, but only at higher altitudes. The Harriers simply refused to fight them, so if the Argentines wanted to get to the ships they had to fly down where the Harriers had the advantage. The same occurred during WWII when US B-17's flew at altitudes where German fighters were struggling, allowing the escorting P-51's to chew them up.
It is not uncommon for extended dogfights to end with troops on the ground shooting down some of the aircraft, as was the case with the Red Baron (or so the Australians will claim).

And also "Australian Army machine gunners on the ground fired at Richthofen, who eventually crashed near the Australian trenches. His initial combat report was that the fight with Richthofen was "indecisive" – this was altered by his commanding officer to "decisive".[2] Modern historical consensus suggests that Australian anti-aircraft gunner Sergeant Cedric Popkin is the person most likely to have been responsible for the shot that actually downed the Baron."

@CrossRoads - your posts explain precisely why I would say that.

WWI dogfights would generally be between 5-15000 ft.  Aircraft could patrol up to 20,000 ft (yes, without oxygen).  The Camel had a service ceiling of 19000 ft, the SPAD XIII almost 22,000 ft.
In WWII, generally between 20-35000 ft over W Europe, under 20000 ft over Russia and in the far east.  Bomber escorts in W Europe started out hanging with the bomber formations just above at perhaps 25-27000 ft, but later when they were sent to range on ahead, they would patrol at 30-35000.  The FW190-A8 had a service ceiling of a bit over 37000 ft, and the Mustang just over 40, but at service ceiling there is almost no spare energy available for maneuvering so you couldn't actually fight at that altitude for any length of time.
In both WW's, once started the fighting aircraft would get lower and lower as they consumed energy, that would normally be available for climbing, in maneuvering for advantage, and in long fights they would end up near the ground.
An interesting aspect of high altitude combat in unpressurized airplanes was the risk of getting the bends from extended exposure to the low atmospheric pressure above 25000.
Today, I would say 20-50000 ft.


text:
What is flight inspection, as provided by Cobham Aviation Services?
At about midnight, I saw a small plane (a Diamond Twin Star) take off from Heathrow, on flightradar24. It then proceeded to fly in irregular loops around North London, at low altitude, 1700ft. The plane had registration G-COBS, and seems to be owned by "Cobham Flight Services", which provides "flight inspection services". Their web page advertises how good they are, without explaining what they do.
It seemed unusual, as such small planes don't normally use Heathrow, and flying low over a city at night also seems unusual. What was the purpose of a flight like this?

I saw this exact same thing. Such weird flight patters and seems to have landed near RAF Northolt. I can only assume it was some sort of military testing. They are know to scan parts of London and zap electronics data from below. I guess "flight inspection" is the perfect cover.

If you're interested in the subject, you might enjoy this article, where a reporter goes along for a ride on FAA flight check operations. It apparently involves a lot of maneuvering and no small amount of nausea, not to mention birdstrikes.

@MajorMajor -- there's really nothing sekret sqwirl about what's going on with navaid flight inspections -- think of it as a test flight to make sure the navaid works, just like your mechanic would test drive your car after doing a bunch of work on it to make sure that all the work is good and he didn't put it back together wrong :) It's just that the stakes are higher for navaids...

Flight inspections are flights performed to measure the performance of the communication, navigation and surveillance (CNS) infrastructure of air traffic control.

Flight tests are required to examine the signals-in-space as received
  at the aircraft after being influenced by external factors such as
  site conditions, ground conductivity, terrain irregularities, metallic
  structures, propagation effects, etc.

source: ICAO DOC8071
In this case the inspection flight seemed to be performed to inspect the performance of the Instrument Landing System at RAF Northolt. The aircraft did numerous approaches on runway 25 and flew across the localizer twice at approximately 11 km (6NM) from the runway threshold. This is a normal procedure for ILS testing.

For those interested in the details of the ILS testing procedure seen on FR24, it is described in section 4-10 of ICAO Document 8071, Manual on Testing of Radio Navigation Aids, Volume I (Testing of ground-based navigation systems).

From their website,

Cobham conducts commissioning, return-to-service, engineering and
  periodic flight inspections in addition to trials work on a range of
  systems including, CAT I/II/III ILS, MLS, PAR, DVOR, NDB, U/VDF,
  TACAN, DME, AGL and PAPI and PSR/SSR.
The specialist capabilities include procedure validation, ADS-B and
  MLAT-systems, ship borne navaids, FI programme management, technical
  investigations, communication tests and trials, windfarm trials,
  flight inspection advice, and training.
Cobham has formal approvals from UK CAA Safety Regulation Group (CAP
  670), UK MoD, INAC (Portugal), ENAV (Italy), British Standards
  Institute (BS EN ISO 9001:2008), Germany BAF, and Air Safety Support
  International OTAR for UK Overseas Territories.

It looks like they test airport/en-route equipment such as approach systems and ADS-B systems etc. This can presumably be done in any aircraft equipped to fly/test those approaches and systems.

The following link provides some information and history of Flight Inspection from the FAA.

I live nearby Frankfurt airport and every few months or so the DFS (German ATC) issues a press release about inspections flights.
Sample from their homepage:

Flugvermessung am Flughafen Frankfurt (Flight inspection at Frankfurt Airport)
Noise disturbance to be expected during the day and at night
14.11.2016.- In the period from 17 to 20 November 2016, calibration flights will be conducted at Frankfurt Airport.
The accuracy of the instrument landing systems of the southern runway and the centre runway will be inspected for landing direction 25 (westerly weather patterns) of the southern runway and 07 (easterly weather patterns) of the centre runway. The calibration aircraft being used is a twin-turboprop Beechcraft Super King Air 350. During this time, noise disturbance is to be expected during daytime and nighttime hours.
Despite the night curfew at Frankfurt Airport, technical flight checks such as calibration flights may also be conducted at night as they would have a great impact on regular air traffic during the day.
The calibration of technical facilities is indispensable for the safety of air traffic. DFS would like to apologise for any inconvenience caused by such flights.

This one was for RWYs 25L and 07C but three months earlier they did similar flights for RWY northwest (07L/25R).
It's interesting (and attracting) that flightradar24 shows the flight around LHR from your question. Next time I hear about inspection flights in my area I'll have a look at flightradar24 too.
Update: A few days ago DFS announced further calibration flights from 16 to 19 February 2017 around FRA/EDDF to inspect ILS accuracy for RWY northwest (07L/25R). I figured out they use (at least) two aircraft, D-CFMB and D-CFMD. This time it was the latter. They flew on Feb 16 (left) and Feb 17 (right):

But the funniest one must have been on Feb 15 from DRS (Dresden) to Berlin (SXF), rendering kinda crop circles:

All pictures from FR24.

From the Flight Inspection Wikipedia entry:

Flight inspection refers to the periodic evaluation of navigational
  aids used in aviation, such as flight procedures and electronic
  signals, to ensure they are safe and accurate. Unlike flight tests,
  which analyze the aerodynamic design and safety of the aircraft
  itself, flight inspection comprises reviewing flight procedures (such
  as routes, approaches and departures) to ensure navigational support
  is sufficient, there are no obstacles and the procedure is reliable.

It may seem unusual, but it is actually a very common procedure, done regularly as part of national and/or international aviation standards, and every time there is a significant change to ground infrastructure which may affect Nav Aids signals.


text:
How does one determine runway orientation without a local wind rose?
We are planning to establish new airport, but then we have no wind rose analysis of the location.
How can we predict what's the right orientation for the runway that satisfies the 95.

If the surrounding terrain is flat then a nearby wind rose analysis could suffice.

Well, without wind-rose analysis you don't even know what the criteria is, do you?

If you don't get a good answer here, you could also try earthscience.SE. Your question is basically "how can I determine the prevailing winds in a given location?", which isn't only relevant to aviation.

Build it 90 degrees from the next closest runway. Murphy's law will then guarantee that both runways always have a 45 degree crosswind.

Assuming that you are not bound by local topography and thus can build the runway in, theoretically any direction you like, there are a few things you can do. First, you could set up a small weather station and record some data. You could then use this data to determine your direction. You can also use a site like this one to see the historical wind/weather data in the area. This will help you get an idea of the prevailing winds at near by.


text:
Does dual given in an approved AATD/FTD under Part 141 count towards the total sim time allowed for ATP in 61.159(a)(6)?
Reviewing 61.159(a)(6), it mentions that an applicant cannot credit more than 100 hours in simulator towards their total aeronautical experience as long as it was conducted as part of a 141, 142, 121, 135, etc. course. I have 33.3 hours (dual received under part 141) of time I logged while a student at a 141 school. I also instruct at a Part 141 school and have 45 hours (dual given under part 141).
Can I use all this time - received plus given - towards my total aeronautical experience for ATP?
All the sims have current LOAs and are maintained by a very big sim department at my 141 School.

Just to clarify, you've given 45 hours of dual as an instructor in an AATD/FTD at a part 141 school. You're asking if those 45 hours of dual given in a sim count towards the sim time allowed for an ATP candidate. Is that correct?

You would have to check with your school to see what parts of your "aeronautical experience as part of an approved training course" counts towards your experience. 141 flight schools with have differences in their flight training courses, so someone who is more familiar with your school's 141 course will be able to give you a better answer on this.

It would all depend on the school you were to pursue an ATP through.  For a Part 61 program, you can only use a maximum of 50 sim or FTD hours toward an ATP per §61.159(4)(ii).  For a part 141 school it may be different depending on the approved curriculum.

Part 121 Airline is the next stop

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text:
Is the weather radar on and active during the whole flight?
The title says it all: Do airline pilots leave the aircraft's weather radar on at all times during the flight and display the data on one or both of the Navigation Displays, or only if clouds/ weather are visible / expected?
I know it should not be active on the ground due to possible radiation harm, so my question relates to the airborne phases climb, cruise, descent.

Airliners typically fly around 36,000' or so. Except in the tropics, thunderstorms don’t get that high. There wouldn’t be much point in having it on all the time. There is a Part 91 pilot on YouTube, stevo1kinevo, who flies a TBM in Florida where there is lots of thunderstorm activity. If you watch his videos, he keeps the Nexrad display on all the time and only turns the radar on when he is close to thunderstorms.

@JScarry I regularly fly at 43,000' - 45,000' and see thunderstorms which exceed our cruising level almost every other flight and have to deviate for them, all over the world.....

Agree.  The US Great Plains tend to generate some epic storms as well.

I thought I remembered that number from the FAA knowledge tests, but I guess I mis-remembered.

Not necessarily; it is the pilot's prerogative to use the weather radar as required. If the weather is clear and the pilot decides that the weather radar display is going to take up valuable space in display, he/she can fly without the weather radar on. Of course, in cases like night flying, it is better to have it on during the entire flight, but it is the pilot's decision.

The regulatory requirements are for the weather radar to be operational only if potentially dangerous conditions are expected en route or for night flying. From CFR §135.175   Airborne weather radar equipment requirements:

(b) No person may begin a flight under IFR or night VFR conditions when current weather reports indicate that thunderstorms, or other potentially hazardous weather conditions that can be detected with airborne weather radar equipment, may reasonably be expected along the route to be flown, unless the airborne weather radar equipment required by paragraph (a) of this section is in satisfactory operating condition.

European regulations are also similar. From JAR-OPS 1.670 Airborne weather radar equipment:

(a) An operator shall not operate:
(i) (1) A pressurised aeroplane; ...
...
unless it is equipped with airborne weather radar equipment whenever  such an aeroplane is being operated at night or in instrument meteorological  conditions in areas where thunderstorms or other potentially hazardous  weather conditions, regarded as detectable with airborne weather radar,  may be expected to exist along the route.

Consider things from a risk perspective.  If the equipment is there, and it provides useful information for safety of flight, I leave it on.  Setting the tilt down can provide orographic information, map water bodies, etc.
Also, I tend to run the electronics in the plane if there is no adverse consequence to doing so.  Electronics tend to be adversely impacted by water, and heat dissipation tends to keep the electronics dryer.
Of course it is not operated on the ground, mostly because the radiation from the unit is harmful in a couple of ways to life, because it may interfere with electronics on the ground or nearby planes, and because it can cause problems with devices like a heart pacemaker.


text:
Are en-route ATC callsigns standardized?
I've seen different callsigns for en-route air traffic control, including Center, Radar, and Control (and Radio?). I suspect the only difference is the geographic location - Center in the U.S. (e.g. Salt Lake Center) and Radar and Control in Europe (e.g. Langen Radar, London Control).
Are there any other differences besides location? (is the location-assumption correct?) If not, why is it not standardized then?

Related

Actually, it is standardized, but not in the way you assume.
The suffix ("radio", "information", "radar", etc.) specifies the type of services offered by the station or, in some cases ("ground", "approach", etc.), the type of traffic or phase of flight handled by the station.
For example, a station named Springfield Radio won't offer radar or ATIS service; if it did, the suffix would be different ("Radar" and "Info", respectively, in this case). Just by a quick glance at the call sign, or overhearing it on the radio, the pilot can know what to expect from them.
Consequently, if Approach hands the aircraft off to Control during approach and landing, the pilot knows that something is probably amiss and can ask for confirmation; but if Approach hands them off to Tower or Tower hands them off to Ground, they know that all is probably well.

There are a number of different "ATC" authorities:
Ground Control☆
Responsible for the movement areas on the physical airport. This includes both aircraft and airport service vehicles. Aircraft refer to this as "Ground".
Clearance Delivery☆
Gives an aircraft IFR (or sometimes VFR) clearance for flight plans.
Tower☆
Manages arriving and departing aircraft, usually takes over responsibility for aircraft as they approach a runway (take-off clearance) or as they approach the airport (hand-over from approach control).
Departure Control☆
Manages the airspace around the airport for departing flights providing separation and routing. Sometimes combined with Approach Control.
Approach Control☆
This is the first authority you talk to that is actually located at the airport. Manages spacing and arrivals and usually assigns runways. Also called "Terminal Control" and may be combined with departure control.
Enroute/Center/Area
This is the authority you talk to when you are going between airports. Usually a center controls a large area of airspace and can manage aircraft in those areas. Here are a list of FAA Centers, called "Air Route Traffic Control" or ARTCC for short. On the radio pilots usually use the term "Center".
Flight Service Station
This is a service provided to pilots but is not an air traffic control authority. Pilots may open/close flight plans or get en-route weather information on these frequencies. They are usually called "Radio", for example, "Stevens Point Radio, N12345 on 131.2"...

☆ - Typically located on the airport which the pilot is operating. This is not always the case though, there are remote towers and satellite airports that may include these services but not have them co-located with the field.


text:
When may commercial pilots release their shoulder harness?
In one answer to a similar question I found a hint to 14 CFR 91.105:

(b) Each required flight crewmember of a U.S.-registered civil
  aircraft shall, during takeoff and landing, keep his or her shoulder
  harness fastened while at his or her assigned duty station.

Now, I assume this also applies to Part 121 operations?
What exactly does that mean with regards to when are the shoulder harnesses released in practice? Is there an altitude (i.e. 10000ft) at which pilots usually release the shoulder straps - is that maybe company-specific?

You essentially have two questions, which I will answer in turn:

When may commerical pilots release their shoulder harnesses when operating under commercial operations rules such as §121
When do such pilots actually release their harnesses in practice

Regarding your first question:
14 CFR 91.105 does generally apply to commercial operators and air carriers. However, §121, §135, and §137 each provide equivalent regulations which duplicate or exceed the language found in §91.105.
14 CFR 91.105 states, in pertinent part:

(b) Each required flight crewmember of a U.S.-registered civil
  aircraft shall, during takeoff and landing, keep his or her shoulder
  harness fastened while at his or her assigned duty station. This
  paragraph does not apply if—
(1) The seat at the crewmember's station is not equipped with a
  shoulder harness; or
(2) The crewmember would be unable to perform required duties with the
  shoulder harness fastened.

14 CFR 121.311 states, in pertinent part:

(h) Each occupant of a seat equipped with a shoulder harness or with a combined safety belt and shoulder harness must have the shoulder harness or combined safety belt and shoulder harness properly secured about that occupant during takeoff and landing, except that a shoulder harness that is not combined with a safety belt may be unfastened if the occupant cannot perform the required duties with the shoulder harness fastened.

14 CFR 135.171 states, in pertinent part:

(b) Each flight crewmember occupying a station equipped with a shoulder harness must fasten the shoulder harness during takeoff and landing, except that the shoulder harness may be unfastened if the crewmember cannot perform the required duties with the shoulder harness fastened.

14 CFR 137.42 states, in pertinent part:

No person may operate an aircraft in operations required to be conducted under part 137 without a safety belt and shoulder harness properly secured about that person except that the shoulder harness need not be fastened if that person would be unable to perform required duties with the shoulder harness fastened.

Under each regulation, the flight crewmember may generally unfasten his or her shoulder harness at any times other than during takeoff and landing, or if the shoulder harness would interfere with performing required duties. The one exception to these allowances is found under §121 in instances where the shoulder harness and safety belt are combined1.
These allowances notwithstanding, a certificate holder may include in its General Operating Manual provisions that flight crewmembers must adhere to requirements that exceed those given by regulation.

Regarding your second question:
In practice I never release my shoulder harnesses from the time I seat myself and fasten my safety belt and shoulder harness until the aircraft has come to a stop and I am ready to leave my seat at the end of the flight. I have also never seen a fellow pilot at my air carrier release his or her shoulder harnesses while in flight. Others will doubtless have different experiences.
Prior to my time with my present employer I have witnessed pilots who make a practice of not wearing the installed shoulder harness at all (given the circumstances I don't think they would have had a very good argument that it would otherwise interfere with performing their duties). I have also witnessed pilots who unfasten both the shoulder harness and safety belt after landing while still taxing at the end of a flight. This later practice is not against regulation2 but may be of questionable judgment in some cases.

1 §121 requirements for combined safety belt and shoulder harness:
14 CFR 121.311 also gives the following, in regards to the requirements for aircraft to be equipped with combined safety belts and shoulder harnesses:

(f) No person may operate a transport category airplane that was type certificated after January 1, 1958, or a nontransport category airplane manufactured after March 20, 1997, unless it is equipped at each flight deck station with a combined safety belt and shoulder harness that meets the applicable requirements specified in §25.785 of this chapter, effective March 6, 1980, except that—
(1) Shoulder harnesses and combined safety belt and shoulder harnesses that were approved and installed before March 6, 1980, may continue to be used; and
(2) Safety belt and shoulder harness restraint systems may be designed to the inertia load factors established under the certification basis of the airplane.

I read this to mean that, for aircraft specified under §121.311(f) above, unless a shoulder harness was approved and installed before 6 March 1980, then the aircraft must be equipped at each flight deck station with a combined safety belt and shoulder harness. Furthermore, under the requirements of §121.311(h), when the flight deck stations is so equipped with the combined safety belt and shoulder harness, no provision of §121 allows for that shoulder harness to be unfastened during takeoff and landing, even if the shoulder harness would interfere with performing required duties. Presumably the approval process for those harness systems would ensure that no interference would be possible.

2 14 CFR 91.107 does generally require that each person on board a U.S.-registered civil aircraft must have a safety belt and any installed shoulder harness properly secured about him or her during movement on the surface. However, this requirement does not apply to required flight crewmembers or to any operations conducted under §121, §125, or §135. See §91.107(b).

Why the downvote? Did I get something wrong?

My guess on the down vote: You very thoroughly address shoulder harnesses during take off and landing, but the question is when are they released in practice. You briefly mention it in your first sentence, but none of the CFR refs address anything else. There may not be any CFRs about any other segment of the flight, though, so there may not be anything else for you to address...

@FreeMan With that in mind I have edited to attempt to more clearly address each part of the question.

IMO, this answer just legalistically repeats "during takeoff and landing", but the crux of the question was when is takeoff considered to be over and when is landing considered to begin. A few words on that would be worth paragraphs of legalese. Some other requirements of this sort use 10k feet as the threshold. You seem to be saying that it's more immediate, i.e., that "during takeoff" means it's technically okay to release the harness as soon as all wheels leave the ground? That's what I thought OP was trying to clarify.

"I never release my shoulder harnesses from the time I seat myself and fasten my safety belt and shoulder harness until the aircraft has come to a stop and I am ready to leave my seat at the end of the flight" -- so you never need to use the lav in flight?

This was an old answer, I see. I now release my shoulder harness sometime between 1500 AGL and shutdown, with a median release point that I would estimate at about 2500 AGL. Is that more helpful?

Company-specific as far as I know. My operation uses flaps retracted for releasing the shoulder harness, and the descent checklist for putting them back on, but I doubt that there is a requirement to pick either of those exact points. Above/below 10,000' would probably work equally well.

Does this mean that the pilots usually spend the flight with just a lap belt fastened as is recommended for passengers?

@FreeMan Yes, 91.105(a) requires the crew to use "safety belts" for takeoff, landing and while en route. And I can't speak for airline pilots, but in light aircraft it's common to just loosen the shoulder straps and then tighten them up when needed, for landing or turbulence. It does depend on the configuration, though: newer Cessnas typically have a car-style seatbelt so there's no separate shoulder part to loosen or remove anyway.

Read the reg, it says during takeoff and landing.  That is all.  Once you are in a departure climb, you can unsecure your harness.  When you are on an approach to landing, you should verify it is secure.  Altitudes are rather irrelevant, because they are not in the regulation.
Naturally best practice is to keep the belts on.  The pilot flying usually has his a little tighter than the pilot not manipulating the controls in the event of unexpected CAT or whatever.
However, the regulation is simple, and as usually is the case with regulations, specifies a minimum acceptable behavior.  If your company manual or policy is different, that is something that is not regulation based.

It's not just best practice to keep the belts on, it's required by 91.105(a) "During takeoff and landing, and while en route"

Forgive me, I was using belts generically, lumping shoulder harness and seat belt together.  The reality is that in virtually every plane I have flown commercially since 1980, there are 5 point harnesses for the front crew positions.  So most of the time it is difficult to take off just the shoulder harness.  Some of the older aircraft, ones which have not been recently refurbished, have separate shoulder harnesses and separate lap seat belts. Also, it is customary to loosen belts a bit for comfort during long cruises, and to tighten them up when there is risk of any turbulence.

One additional note, we all have experiences, but I clearly remember flying a piston aircraft, over the Blue Ridge Mts area, and suddenly having my head slammed against the interior ceiling of the aircraft.  My belt was snug, and I was close to getting seriously hurt or LOC.  Since then I make belts real snug when there is any chance of turbulence.


text:
What are the differences between the Avro RJ85 and the BAE 146-200?
As far as I understand, the Avro RJ is a newer version of the BAE 146? What are the exact differences?

The main difference between the Avro RJ and the BAe-146 is the engine- The RJ has Honeywell LF 507-1F, which is developed from the Lycoming ALF 502R-5 used in 146. The main difference between the engines is that the 507 has more LP turbine stages (2 Vs 1), sightly more thrust (31.5 KN Vs 31 KN) and has a single-channel FADEC with hydro-mechanical backup.
Visually, the 146-200 has a small triangular bump in the rear fuselage to prevent tailstrike, while it isn't there in RJ85.


text:
Where can I find an example of a raw 1090ES message for testing?
Can anyone provide a raw 1090ES Aircraft Operation status message (DO-260B standard) so I can test my decoding logic?

Related

You may not see ADS-B callsign( mode s flight id) changed after completion of flight. I dont think that is something changes during flight, unless pilots are instructed to change to a default number. But even then, pilot might put transponder to stby mode and go silent before flight id change.


text:
How is NASA going to get high fuel economy on the X-57?
This X-plane is meant to fly soon.

It's a modified Tecnam.
The propeller direct wash over the wings, increasing lift. This allows the use of a smaller, high-aspect ratio, low drag wing.
But this isn't quite clear to me. Here's what I know about this.

Light aircraft have oversized wings for cruise, needed due to a mandatory minimum 61 knots stall speed, and the lack of cabin pressurization generally prevents them flying high enough to make good use of the extra wing area at higher cruise speeds.
The propwash from the Maxwell would act like a blown flap at low speeds, achieving the above requirement without a large wing but presumably sufficient redundancy to not matter.
At cruise however, the propwash would increase friction drag by causing faster airflow over the wings, and possibly interfering with any laminar flow.
The giant propellers at the tips are somehow meant to reduce induced drag - but how?
This is a glorified blown flap.

What am I missing?
EDIT: I just discovered/remembered that at cruise the inner propellers fold to reduce drag. But the point remains: what is so special about this glorified blown flap?

Besides that it has electric propulsion?

@zymhan Yes yes thank you. I think it does. OK, dupe this.


text:
How do I compare cruise fuel consumption with overall fuel consumption?
I've read, that the Otto Celera 500L consumes 7.8/100 L/Km of fuel, which is supposed to be very low. That plane seats 6 supposedly, so it's 1.3/100 L/(Passenger Km) So, I'm checking out the tabble in the Fuel Economy of Aircraft Wikipedia page - but there, the figures are for an entire flight - short haul, medium range, long haul etc. - but per flight.
How do I relate the cruise figures to the whole-flight figures? And - shouldn't fuel economy figures include a cruise component and a takeoff + landing component, separately?

This aircraft is basically vaporware at this point, so everything about its performance should be taken with a large grain of salt.  Also "should" data be broken down into whatever components, for a vaporware aircraft, is pretty well in the realm of opinions rather than hard facts.

@RalphJ: Yes, fixed. But the question is not really about the aircraft, more about comparing figures in principle, as the title suggests.

It's not totally clear what you are asking:  Where to get the data, how to separate cruise fuel burn from climb and descent, or how to "compare" them...  Which one is it, or are you asking for all three?  If you are looking for a specific model aircraft that information is typically in the performance charts in the Flight Manual.  So the short generic answer is to get into the performance charts...

@MichaelHall: The second and third items, I guess.

Shouldn't fuel economy figures include a cruise component and a takeoff + landing component, separately?

You are correct in presuming that whole-flight fuel consumption numbers are comprised of three main phases of flight:  Take-off/Climb fuel, Cruise fuel, and Descent/Landing fuel.  Fuel consumption on each segment is derived from performance charts in the aircraft flight manual, and then added together as total fuel burned.

If you have access to performance charts and are computing actual fuel burned for a specific leg you would already know it.
However, if all you have is a total and are asking whether Wikipedia (or any public source) "should" display each phase of flight separately I would suggest that while that might be your personal preference, it would probably be more information than most users care about.

How do I relate the cruise figures to the whole-flight figures?

You can't, at least not from the information provided in the link.  Once the fuel has been totaled you cannot work backwards without knowing at least two of the three subtotals.
(It would be like trying to determine whether 18 is the sum of 6, 6, & 6, or 7, 6, & 5.)


text:
Tail numbers not starting with N, with domestic US carriers?
I'm looking at some of the on-time performance data made public by the US Bureau of Tranport Statistics, e.g. through here. These have the tail numbers of the aircraft used in commercial intra-US flights over the years.
I'm seeing that, occasionally, tail numbers are missing. But in some cases they're actually garbled (e.g. N105@@) - or just perhaps uncommon. Specifically, I'm seeing, among others, tail numbers such as:
89869E
91469E
9149E
A367NW
EI-BWD
HZO
M67153

Can some of these be "legit"? That is, could the above (and similar) strings be actual tail numbers of aircraft which were used in commercial domestic US flights?

Note that we're talking about entries from years between 2001 and 2008.

Nearly all countries’ tail numbers start with an ITU prefix, and EI- is for Ireland. The others all appear to be garbage data.

This question seems closely related and might answer your question? At least about whether it’s possible for non-US aircraft to be used in domestic commercial operations.

@Pondlife: It might explain one (or some?) of the tailnums, but not all of them I think.

A367NW looks garbled. There's an N367NW which is a former Northwest Airlines A320.

To get better answers, you might like to clarify if you're asking a) if it's possible that non-US aircraft are being used for domestic commercial flights (already answered in the question I linked to); b) if the specific tail numbers you listed are, were or could be real; or c) something else?

@Pondlife: See edit.

Does this answer your question? Is commercial domestic service using foreign registry aircraft allowed in the USA?

Yes, these can be legit.  For example, EI- means the aircraft is registered in Ireland.  Others look corrupt, though.  HZ-AAA is Saudi Arabia, but your HZ example looks too short.  The examples starting with four numbers don't match any country's pattern.
https://en.wikipedia.org/wiki/List_of_aircraft_registration_prefixes
The examples here that start with a string of digits all resolve to actual aircraft, if you prepend an N to them.  (Commenter Ralph J suggested this.)
Corrupt data wouldn't be too surprising.  For 2005, for example, 15000 of the 594000 entries had no tail number at all.

What would the digits+E numbers mean?

@einpoklum Could be military

@einpoklum or coordinates rather than aircraft registration codes or flight numbers

@jwenting: It's the "tail number" column of the on-time performance data; and there is no column with coordinates...

@einpoklum doesn't mean it's correct :)

I'd presume that anything that's 5 characters without a leading N or other obvious explanation like the EI-xxx example is simply a case where the N was omitted.  So when you have 1234X, I'd presume that this is meant to be N1234X, unless a better explanation is found.  If you find the same aircraft showing up multiple times as both 1234X and N1234X then I'd say you have confirmation that it's just a missing N in the certain cases.  Sounds like you have moderately low-quality data you're working with.


text:
When do commercial aircraft tail numbers change?
Each (large, commercial and most other) aircraft has a registration number, painted or stickered on its hull: the tail number.
I was under the false impression that tail numbers don't change, and that a number identifies an aircraft until it's decommissioned. That's not true, apparently! This article, for example, explains how new owners may want to change numbers when they buy aircraft.
My question: Under what other circumstances do tail numbers of commercial aircraft typically change? Other than changes-of-ownership?
Notes:

I'm not asking about considerations for changing tail numbers during ownership changes. That's covered.
Of course, someone can arbitrarily change a tail number on a whim, but that's probably very rare; I'm asking about somewhat-common situations in which tail numbers are changed.

Motivation: Want to be able to use tail numbers to distinguish different aircraft, but need more information to qualify that assumption. So, I realize different owners may invalidate the assumption; looking to qualify it further.

Aside from ownership changes, tail number change is very rare: The cost to change the tail number with the same national registry, on the aircraft itself and in the maintenance logs plus the cost of the aircraft being out of service for some time will far outweigh any minor cosmetic benefits.
The only reason I can think of is changing the registration to a different country for tax or regulatory cost savings. Since the first 1-3 characters of the tail number are a national prefix, it must changed in that case. This also often coincides with a change in ownership, though possibly just to a shell corporation to make the registration in the new country allowable, which then leases it back to the original owner.

I was under the false impression that tail numbers don't change

Tail numbers (AKA registrations) are changeable by definition since each country is allocated codes with different prefixes and formats. If an operator from country X buys an aircraft from an operator in country Y, then the tail number must will most of the time be changed to a valid tail number of country X. Depending on local laws, in some rare cases a tail number of another country will be used, for tax purposes (much more common with sea vessels). This is why some Aeroflot aircraft have VP-B* registrations that belong to Bermuda.
What does not change is the manufacturer serial number (which may be analogues to a road vehicle VIN).
I think the source of the confusion is that the Wikipedia article that you linked to uses "tail number" of civil and military aircraft interchangeably, and that is wrong. Military aircraft's tail numbers do not conform to their countries' ICAO-issued civil registration format, and they may or may not be changed whenever said air force want.

Already know that different carrier + same tail number may mean different aircraft

This assumption is wrong. Tail numbers are unique. However, they can be re-used over time.

Under what circumstances do tail numbers of commercial aircraft typically change? That is, other than arbitrary whims (which I assume are rare), when do airlines/aircraft owners go through the number changing procedure?

As mentioned above, the most likely case is when an aircraft is being bought from an operator from another country than the previous operator.
Sometimes the new operator will change the tail number even if the aircraft was bought from an operator in the same country in order to fit the registration scheme that said operator may use (for example, N737* for 737 aircraft, N747* for 747, etc).

Other than the mentioned cases above, it's impossible to answer this question in general terms. Every operator may or may not change tail numbers of aircraft it buys. An operator may even decide to change tail numbers of aircraft it already owns just because.

This doesn't answer my question, though. Interesting to know about the mfg number.

@einpoklum-reinstateMonica I added a direct answer to your question in the end

I already know that tail numbers often change when aircraft change owners. Are you saying that, other than in these circumstances, tail numbers almost never change?

@einpoklum-reinstateMonica It's impossible to answer in general terms. An operator may change or may not change the tail number of aircraft it buys.

Again, I'm not talking about purchases. What are other circumstances in which tail numbers are changed?

@einpoklum-reinstateMonica Again, this question can't be answered. It is not set in stone.

I'm asking about what is somewhat common, not about what happens always.

@einpoklum, it can be changed whenever the owner feels like re-registering it, but given the amount of paperwork they only change it if they have a good reason for it, and those are listed in the answer.

There is one more reason. When returning an aircraft that was stored to service, it's registration may have expired, so it needs to be re-registered and usually gets a new number (of course returning stored aircraft to service is usually done after purchase, so the other reasons apply anyway).

The most common time for a tail number to change would be when an aircraft changes ownership. However, if the airplane is staying in the same country, it may not be worth the paperwork to change. Some examples include US Airways aircraft like N167US retaining their registration with American, and AirTran aircraft like N937AT retaining their registration with Delta.
Although it's possible for an airline to operate foreign-registered aircraft, a foreign sale is the point where it may make more sense to get a new registration.
The livery is the most important part for brand image of the airline. Few people pay attention to what the tail number is, and it's more of a regulatory/paperwork detail. Records such as for maintenance may refer to the tail number and it makes more sense to leave that consistent even if the ownership changes. Unlike private operations, commercial flights will typically be identified to ATC under a callsign rather than their tail number, so that is not as much of a factor.
A smaller operation that may want to keep some sort of registrations scheme might find it worth changing the registration on aircraft when they change hands.

But again, my question is about other circumstances in which tail numbers are changed...

Note that the operator-specific suffixes are somewhat specific to the USA. In Europe most aircraft have a five letter, including country prefix, registration with no obvious pattern.

In the US an owner can change it quite simply. The FAA charges $10.00 to assign a new N-number to an aircraft. There's no additional charge if you can accept whatever number the FAA assigns. You can however reserve a special N-number for a fee of $10.00. Even if you don't have an aircraft, you can reserve a special N-number, though it will cost you $10/year to hold it. It's all spelled out on the FAA web site under Special N-Numbers, Changing N-Numbers

The rules are different in different countries.
In some countries the aircraft gets its registration, and keeps it forever (the registration may be suspended if the aircraft transfers to a different country, but will regain its original registration on return).
In some countries you cannot choose the registration, the authorities do that. In some countries, the owner can choose a registration, and change it as often as they want.
In some countries you have to re-register the aircraft every few years (3 for FAA-land??), in others the registration is for life.
So, it varies.

Does re-registration involve a tail number change?


text:
What are packs on aircraft?
I've been watching YouTube videos and when they're going through the checklist they say "packs off" can anyone elaborate?

Searching here for "packs" would have answered this question. It's a useful resource.

Most jetliners are equipped with "p-a-c-k-s" which stands for
  Pressurization Air Conditioning Kits".

The air conditioning (A/C) packs are usually located at the lower wing/fuselage root fairing beneath the fuselage.

source
On some jetliners (Douglas Aircraft DC-9 Series) the A/C packs are located in the tail, while other aircraft such as the McDonnell Douglas DC-10/MD-11 and Lockheed L-1011 are located in the front of the aircraft beneath the flight deck.
Nearly all jetliners have two packs, although larger aircraft such as the Boeing 747, Lockheed L-1011, and McDonnell-Douglas DC-10/MD-11 have three.

I suggest adding a paragraph on why the packs are turned off for takeoff.

Packs are normally on for takeoff unless you are doing an unpressurized takeoff for some specific reason.  If you have an APU running they can be on APU bleed instead of engine bleed so you don't have to take the performance hit.

This was very useful! Thank you

Good illustration +1, note there is no consistent definition for the (supposed) acronym PACK. Passenger Air Conditioning kit -- Pneumatic air conditioning kit -- Pressurization and air-conditioning kit. Other variations can be found, leading to pleonasms like "pneumatic air cycle kit". Airbus seems to use "AC pack", with pack being a shortcut for package, like in "A pack with a seized ACM must be switched off on ground".


text:
Are aircraft engines classified as DAL A or DAL B?
I am confused regarding the Design Assurance Level (DAL) of aircraft engines. I attended a seminar in which the speaker mentioned aircraft engines as being DAL level B; when we asked about it, he answered that it's not required by the FAA to have two engines running because an aircraft is capable of flying with only one engine. Hence, it's classified as DAL level B.
If I'm not wrong, the FAA states that an commercial aircraft should be able to fly with one engine with for at least 1.5 to 2 hours. So was the speaker right about the DAL classification?

From reading the wikipedia article, it looks like DO-178B only applies to software.  So when you ask this question, do you mean the mechanical components of the engine?  Or can we safely assume you mean the software components controlling the engine?

I'm assuming this is applying to the software, as that is what is assigned a DAL by the manufacturer (and accepted by the FAA) during the DO-178B/C process.

DAL started in the software world with DO-178, but it has been extended to the entire development process.  This is documented in ARP4754A Guidelines For Development Of Civil Aircraft and Systems and ARP4761 Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment.
But to the direct question, 14 CFR 33.75 Safety Analysis, describes the safety levels required for the engine.  Matching the wording there

(3) The applicant must show that hazardous engine effects are
  predicted to occur at a rate not in excess of that defined as
  extremely remote (probability range of 10−7 to 10−9 per engine flight
  hour).

with ARP4761, it is describing DAL B.  So I would have to agree with the speaker.
But I will offer one point of personal experience which is that one FAA certification officer insisted the DAL for the FADEC software should be DAL A.  The argument is that a common mode fault in the FADEC software could result in simultaneous loss of both engines.
One other fine point of certification is that complying with Part 33 allows you to get a Type Certificate for the engine.  That doesn't mean it meets all the requirements necessary to allow an aircraft with that engine installed receive an aircraft Type Certificate (under Parts 23 or 25).

Assuming a two engine aircraft, this is wrong.  While the FHA (see SAE ARP 4761) may have a case that says the loss of one engine is Major (Part 25 DAL C) The FHA should also have a case that says loss of both is Catastrophic (Part 25 DAL A).  Catastrophic requires DAL A or two things that are DAL B that are dissimilar. Or rather, two things that use a dissimilar development assurance process, see SAE ARP 4754A.  Since the fine folks that make the FADEC are not going to do that, you are left with DAL A.

I think you will find that quite a few FADEC's are DAL B.


text:
Why are most runways laid out in a generally East-West direction?
Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the runway's heading in decadegrees. From what I have read, most airport runways are aligned along an East-West corridor. Why is the North-South direction rarely used?

My guess is due to Earth's rotation, E-W winds are more common? Maybe a good question on earthscience.SE.

Runways are aligned with prevailing winds so, if the observation about alignments is correct, I agree that the underlying question is more about Earth science than aviation per se.

So if that's the case then any N-W winds would be cross winds. I'll ask this in that forum then.

If OP would like to know why the runways are aligned the way they are like the question says, this SE is appropriate.  If OP wants to learn more about why the winds blow the way they do, that is for earthscience.SE.

This map shows the orientation of runways around the world: https://trailsofwind.figures.cc/ It helps give you a sense of the regional patterns.

While there are many exceptions to east-west runways, generally speaking prevailing winds (which blow from a single direction) blow east-west rather than north-south. It happens because of Earth's rotation generates Coriolis effect.

There are other wind patterns besides prevailing winds. Trade winds occur near the equator and flow from either the north or south towards the equator. They curve towards the west due to the spin of the Earth. Polar easterlies blow close to the north and south poles. They blow away from the poles and curve east to west.
Hence, most of the runways are Eastish-Westish (not exactly East-West).

Don't these prevailing winds have more to do with solar heating patterns (and, thus, formation of Hadley cells, Ferrel cells, and polar cells ) than with the Coriolis effect? Coriolis effect does explain why cyclones and anti-cyclones form around low/high pressure centers, though.

Runway directions are largely chosen both for geographic land features of the site of the airport as well as the average local wind directions. As most winds blow from  West to east in the continental United States, most runways will be oriented approximately in that direction. There are some sections of central Kansas and Oklahoma which have runways predominately oriented to in north south heading due to the winds blowing largely in a latitude parallel or approximately thereof in that region.

Though note that the asker is in India, most of which is south of most of the continental US.

Yeah I had to look google maps to get an idea what's he talking about. I follow NBA but still get eastern and western conference teams messed up :D

There are also a good number of runways in the western US that are oriented north-south, because they're in valleys between mountain ranges - Reno, San Jose, and Salt Lake City are major commercial ones I can think of, plus numerous GA fields.

"... due to the winds blowing largely in a latitude parallel or approximately thereof..." do you mean longitude / meridian? Parallels (curves of fixed latitude) run east/west while meridians (great circles of fixed longitude) run north/south.

I haven't seen the East/West bias that you reference, runways are typically built where they make the most sense.  If there are prominent geological features such as mountain ranges or hills that could affect the approach, the designers may decide to construct the runway so that approaches and departures are not near the obstacles.
Populated areas are another concern, if an airport is near a town, the designers may direct the departures and arrivals away from the town in order to limit the noise.

What I meant by E-W is most of the runway bearings are 27-90 or in and around that marking but I don't remember reading about a 00-90 runway.

Do you have citations for these claims? Obviously, there's not much you can do about geological features, but a lot of airports are old enough that keeping things quiet for the locals wasn't really considered an issue. (And one might expect the modern solution would be to build a new airport farther away from the town to avoid noise, rather than using a badly aligned runway.)

Yeah I messed up there its should be 09/27 and 18/36 as you mentioned.

@Huntkil OK -- no worries. Shame it's too late to edit your original comment. I'll delete my response but you should probably leave your reply so people don't get confused.

@Huntkil There are lots of 18/36 (or around that) runways. They just aren't the most common orientation. The primary airports in Nashville (KBNA,) Tampa (KTPA,) Orlando (KMCO,) Seattle (KSEA,) Washington, D.C. (KIAD,) Memphis (KMEM (TN, USA, not Egypt,)) and Salt Lake City (KSLC) all have North-South orientation for their primary runways, for example.


text:
Why have helicopter top speeds not increased much over time?
With advancements in technology why there isn't much increment in helicopter top speeds from what they were in the 1980s? We have newer designs like the Eurocopter X3 which is a hybrid, but the speed is still limited to 300+mph.

Neither have airliners', nor even fighters'...

It's because of damned environmentalists.

environmentalists ? Because of noise ?

@Zeus we have but its not feasible for fighters whereas airliners have increased their avg speed. Mach .7 to .8 is optimum for them to operate.

@Huntkil not really. The current long-range airliners have max cruise around M0.85, which is slightly less that the airplanes from decades ago could offer (VC10 had 0.92 or so, even 747 can 0.88 I think). Similarly, nearly all Gen 2-3 fighters were Mach 2+ aircraft (some even M3), whereas later designs are commonly <M2 (F-35 is M1.6, for example).

@Zeus Check this https://aviation.stackexchange.com/questions/21987/why-is-the-maximum-speed-of-current-fighter-aircraft-lower-than-those-from-the-1?noredirect=1&lq=1. As far as airliners are concerned they focused more on being economical rather than faster one of the reason we never saw another concorde. Its not that we can't develop it's just that we don;t want to. But incase of helicopters there is no technological advancement that helps in increasing the speed. We have new design but not much advancement otherwise.

Yes, but your question is generic enough to apply to many things. It could be asked in exact same words about airliners or fighters. That was my hint: perhaps, "advancements in technology" are not very relevant here (or they are not that great really).

The underlying limit is that the forward-moving blade tip must remain subsonic, and the receding blade must not stall.  Hybrids do better than conventional or compound helicopters because the rotor can be slowed when the fixed wing picks up some of the lift load -- but this only solves the forward blade tip speed issue; unless the rotor can be operated at zero lift, receding blade stall is still a problem.
Some futuristic designs have proposed completely halting the rotor in forward flight (see the aircraft in the movie The Sixth Day with Arnold Schwarzenegger -- cheesy movie, but the aircraft were based on a real concept), using an airfoil shape for the rotor blades that can develop lift with either edge forward.  Others have proposed completely folding the rotor once forward speed is high enough for the fixed wing to support the craft -- but as far as I know, no flying example of either of these concepts has been built.  Until they are, the same speed limitations apply to helicopters and autogyros that were discovered in the 1930s, only partially mitigated by hybrid configurations.
Bottom line is, a helicopter's niche is in going slow, not going fast.  Other VTOL solutions exist for high speed (thrust-hover jets like the Super Harrier and F35 are supersonic).  Attack and high-rate maneuverability in hover are the special domain of choppers; high forward speed is not.

retreating blade problem could be (has been?) solved with coaxial stiff rotors where the retreating side no longer needs to generate equal amount of lift as the proceeding side, e.g. Sikorsky S-97.

@user3528438 These rotors, however, still need to keep the proceeding blade subsonic.  Various designs have been proposed to allow slowing the rotor enough to keep the proceeding blade subsonic (retractable blades in a disk/dome structure, halting/swept blades like in Sixth Day, etc.  None have yet been built.

@ZeissIkon - to be fair, at least 2 stopped rotors designs have been built...they either just did not fly for programmatic reasons (Sikorsky S-72 X-Wing) or did not successfully transition between forward hovering and forward flight during flight tests (Boeing X-50 Dragonfly).

@user3528438 Kamov has been doing that for years (coaxial) but have not materially increased the speed of the aircraft. (For a variety of reasons). When S-97 is a reality, rather than still under development (yes, prospects are good) your use of that example will carry more weight.  X-2 would have been a better example, given that it broke some records.


text:
What is this aircraft with elaborate folding wings?
I noticed this plane in the background of this car advert. Can anyone identify it? I'm assuming that may have been used on an aircraft carrier, hence the elaborate folding wings?

That is a 944 cabriolet and it can really fly.

@Dave I am trying to find something untrue about this comment... but I simply can not

Fairey Gannet ECM.6, c/n F9311, stored at White Waltham Airfield in the county of Berkshire in England. This place is incidentally where the Fairey Aviation Company built and test-flew the Gannet. An aerial picture from Google Maps:

Farey Gannet XA 459 at White Waltham Airfield. Google Maps
In Feb. 2020 the aircraft was Finally moved to Solway Aviation Museum to be heavily restored for public display. The museum published at this time this video about the history of Farey Gannet in general and this airframe in particular.
The wings can be folded in order to park the aircraft on a carrier deck, or on its storage areas. Unfolding the wings (video).

Fairey Gannet ECM.6
Fairey Aviation was a manufacturer which worked a lot with the British Royal Navy's Fleet Air Arm (FAA). With the role played by German and Japanese submarines during WW2, the FAA reinforced its anti-submarine warfare. Fairey Aviation developed the carrier-borne Type Q, later renamed Gannet version AS.1 quickly upgraded to a more powerful AS.4.

Fairey Gannet AS.4. Source
The prototype first flew on 19 September 1949 and made the first deck landing ever by a turboprop aircraft, on HMS Illustrious in June 1950. The anti-submarine role was later taken by helicopters, and AS.4 versions were converted for electronic countermeasures (ECM.6). A third seat was later added over the wing trailing edge for a second observer. This disturbed the airflow over the horizontal stabilizer, requiring the addition of small finlets:

Fairey Gannet ECM.6 with three seats. Source: Gothic-Air

Fairey Gannet landing on Australian HMAS Melbourne. Picture David Tomkinson, source
The Fairey Gannet was powered by a dual Armstrong Siddely Mamba, driving two contra-rotating propellers. One engine could be shut down in flight to conserve fuel if required:

Fairey Gannet with one engine shut down, source
XA 459 RN
A total of 348 Gannet were built, this particular airframe is c/n F9311 registered XA 459 RN for the Royal Navy. It entered 814 NAS in March 1957 as AS.4. Here at RNAS Culdrose in 1976, after it was converted into ECM.6:

Fairey Gannet ECM.6 at RNAS Culdrose, 1976. Photo by Ray Barber at flickr
The aircraft was decommissioned in 1978 and later displayed at Wales Aircraft Museum (Cardiff EGFF):

Fairey Gannet ECM.6 at Wales Aircraft Museum, 1982. Photo by Chris England at ABPic
The museum was disbanded in 1996. The Gannet was then acquired by private individuals in order to restore it. However tragical events prevented the restoration. It was finally bought by White Waltham airfield in 2006.

White Waltham from 2006 to Feb. 2020

XA 459 at White Waltham. Photo by Renegade53 at ipernity

XA 459 at White Waltham. Photo by Jon Wickenden at Flicr
Ian Meredith told us in February 2020 the Gannet was moving to a new place:

Tonight the Gannet and its spare engine(s?) was aboard a low loader
for a UK museum. A place of restoration, a place in the dry.

This place is the Solway Aviation Museum at Carlisle Lake District Airport. On the move:

Fairey Gannet XA 459 moving to its new place, Feb 2020. Source.
Solway Aviation Museum since 2020

Video of its arrival.

Restored:

At Solvay museum, 2023. Photo Richard Vandervord, source.

More about the aircraft:

Exhaustive description of the Fairey Gannet: Alchetron
Pictures: Fleet Arm Association of Australia
Pictures: Flickr
History: Stephen Metcalf's page
History: South Wales Aviation Group

Very impressive that you found not only the type of plane, but the actual plane in the picture.  Nicely done.

shame to see an aircraft left to deteriorate so badly, especially one earmarked for a museum. At the very least put a tarp or some other shelter over it...

Wow, fantastic. I am very impressed that you answered both my question and all the questions that I hadn't even thought about asking until now! Thanks for your time.

@tallpaul: Actually a real pleasure. But I need to say that @ claudio costa and @ jwenting were the first users to find the type of aircraft.

how in the seven heavens did you find the specific airframe?

This answer deserves to commemorated in the Hall of Good Answers

Even though one of the engines could be shut down to conserve fuel, there was a spate of failures due to the engine re-start which was necessary for a safe recovery onto the deck so shutting down an engine in flight (and feathering the propellors) was banned. This happened in the early / mid 70s and affected the AEW3 variant (of 849 B flight).

That is the ugliest plane I have ever seen.

The aircraft is the Fairey Gannet. It can be identified easily by its distinctive Z-shaped double folding wings, which makes it extremely compact for storage aboard aircraft carriers. The image below shows the aircraft with the wings unfolded.

Fairey Gannet T.2 (XA508) in Midland Air Museum; image from plane-crazy.k-hosting.co.uk
The aircraft was used primarily by RN as an ASW aircraft (which appears to be the version in question), though it was also used in other roles like AEW, COD etc. The aircraft also has distinctive contra-rotating propellers driven by Armstrong Siddeley Double Mamba engine, which is basically two Mambas mounted side-by-side and coupled through a common gearbox to coaxial contra-rotating propellers.

The Double Mamba?!?!? MegaMind would LOVE this!!!!!

And there is one left flying Gannet, AKA "Janet"

That is without a doubt the ugliest airplane I have ever seen.

It's a Fairey Gannet. British airplane used for anti submarine warfare

Has two engines also.

@LuftBier it doesn't. It's a single engine that's built out of bolting 2 smaller engines together. Was done more often at the time, the Germans started doing it for their largest bombers in WW2.

It looks like a Fairey Gannet to me, but I'm not 100% certain.
https://en.wikipedia.org/wiki/Fairey_Gannet
https://en.wikipedia.org/wiki/Fairey_Gannet#/media/File:Fairey_Gannet_XG797.jpg

authors: Bob Jarvis - Слава Україні


text:
How can I log simulated instrument time and approaches in a single-place aircraft?
Is there a way to log instrument approaches in VMC when all you own is single-place aircraft? (or aircraft with only one pilot station - I own a Long EZ). The regs seem to indicate that I have to rent another aircraft, which seems to defeat the entire purpose of maintaining currency, as I would be logging my approaches in an aircraft of a different type, with potentially different avionics.

If you are talking about practice approaches under VFR with a hood and safety pilot you ought to clarify that.  Because if you are flying actual IFR approaches under IMC then there should be no problems keeping current, right?!

Remember, maintaining currency is different than maintaining proficiency. Proficiency is very important. But, currency is the crux of this question.

@Michael Hall, Yes, that is what I meant. Unfortunately, actual IMC weather is rare here in Arizona (Prescott).

@Dean,  "Currency" is statistics about how often and how recent an individual has performed an activity.  I would think the objective of tracking currency IS to maintain proficiency. Can't think of any other reason to remain current in an activity.

@CharlesBretana - Currency is meeting the regulatory requirements to fly a particular kind of operation. Proficiency is your ability to perform in that particular kind of operation. For an instrument rated airplane pilot-in-command, currency would be performing HIT 6 in the preceding 6 calendar months in any airplane. Proficiency would be being comfortable in performing an IAP down to minimums through the recent practice and experience of actually performing an IAP in the actual aircraft you will be flying. Currency in a TAA turbine multi does not make you proficient in a steam-gauge single.

@CharlesBretana - Think of currency as the absolute minimum standards to call yourself a pilot. Proficiency is actually being a good pilot. We should be shooting for proficiency. In doing so, we will invariably meet currency.

@Charles Bretana, in your question you mention “the purpose of maintaining currency” and later lament the rarity of IMC weather in Arizona.  This begs an obvious question, what is your actual need to maintain currency?  If it becomes too difficult why not simply let it lapse?  It may be more cost efficient to just get a fresh IPC with your flight review, or before any cross country where you might want to use IFR.

Because I need to be Instrument current for several other reasons. One, I am a CFII, Second, I take the wife on cross-country trips where the weather is not reliably VMC, notably, Southern California, and the MidWest, third, I am in volunteer organizations where I need to maintain instrument currency to potentially respond to callouts when weather is IMC.  (CAP, etc.).

Yes, I understand the definition of "currency". That's exactly the point I was making. Why does the FAA require currency if it doesn't mean proficiency? If an activity has no safety of flight implications, or does not increase proficiency, then should be no requirement to do it regularly, or, it should not count. Do we require pilots to file and log a certain number of Flight Plans every year? Can you regain SEL takeoff and landing currency in a Helicopter? No, because they would not reflect an increase in Safety-Related proficiency in the associated activity.

Unfortunately, the only way for you to get simulated instrument time will be to rent a dual-control aircraft, or to use an approved simulator. Since you can do back-to-back approaches in a simulator, you may be able to find one that charges almost as little as the equivalent amount of fuel in your Long EZ. Especially since you can forego, startup, run-up, taxi, takeoff, landing, and shutdown.
The alternative to the above is to plan on dropping everything whenever you have a suitable IFR day, and go flying. Surely, there are a couple of IFR days in which the weather is not too severe every six months.
If you can deal with the fact that your flight time will not be within your control, you could partner with another aircraft owner of a two pilot place aircraft. That pilot will need a safety pilot as well. Then, you can just alternate who is under the hood.
Another, less convenient and effective, but more productive option is to schedule and budget a regular flight and ground lesson with a CFII once a year. If you make this a recurring lesson with the same career instructor, you can coordinate with them to make this a combination IPC/BFR. This and the random IFR day you may get in a years time should keep you current. It also has the additional advantage of possibly learning something new or relearning something forgotten.
All of the above options address the issue of staying current. None of them address the issue of staying proficient in your aircraft with your avionics. For this I suggest making half of our VMC approaches as actual or practice IFR approaches. You may not get the visceral experience of being in IMC. But, it will allow you to practice your proficiency.

did you possibly mean "cost-effective" in last paragraph?

@quietflyer - Although cost-effective is a valid point, I meant time-effective. There may be a period of time when the pilot who tries this method will not meet currency requirements.

This FAA document amplifies on what Dean wrote: https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2015/info15012.pdf  You don't have to be in IMC all the way to the DH/MDA to log an approach in actual IMC, but there has to be actual or simulated IMC to log it for currency.  And single-seat, the "simulated" option is unfortunately out.

I already have plans to exercise your last suggestion. Obviously I do not wear a view-limiting device as it is VMC out and I need to exercise good visual lookout for other VFR traffic. I do think about and feel a bit anxious about the little heads-down time on the instruments that I need to invest to fly the approach properly. But it is necessary to become proficient with the new flat-screen avionics - the menu structure on these things requires that you practice, practice, practice...

@CharlesBretana - Simulator time may be your best option in this case. It will give you a nice safe environment to practice your buttonology. It will also count towards your currency. In lieu of that, I would invest in a battery charger. I spent a lot of time off the Hobbs just sitting on the ground practicing the G1000 with the  aster on and the engine off. Another option is procedural training with a tablet app or even a set of pictures of the the avionics. It really is just a matter of practice, practice, practice.

And as @RalphJ has pointed out, an IFR day at your local airport may still be pretty close to VMC and still count. Just as long as you have a stable atmosphere. There are plenty of times when a broken layer still keeps you clear of clouds. For that however, you will need to be current. If you are not proficient, I would advise a two-pilot airplane with a second pilot for that, though.

Yes, I think that is my best option. I got one approach last weekend flying to SoCal (Camarillo) to visit daughter. The June Gloom (May Grey) Marine Layer, had IMC conditions that allowed me to fly and log a VOR approach.


text:
What is the ambient temperature used in RTCA/DO 160?
I was going through RTCA/DO 160D for some work-related issue. I went through the whole document but nowhere does it define what the "ambient temperature" value is? In one place it defines +15 to +35 degrees Celsius as one of the parameters for ambient conditions. Does anyone know what is the value of ambient temperature, or it is generic room temperature of 20-25 degree C?

Ambient is the conditions in the test lab.  DO-160 defines it in sec 3.5:

3.5 Ambient Conditions
Unless otherwise specified, all tests shall be made within the
  following ambient conditions:
a. Temperature: +15 to +35 degrees Celsius.
b. Relative Humidity: Not greater than 85 percent.
c. Ambient Pressure: 84 to 107 kPa (equivalent to +5,000 to -1,500 fi)
  (+1525 to -460 m).
When tests are conducted at ambient conditions that differ from the
  above values, the actual conditions shall be recorded.

So anything within this range is acceptable and if it isn't within the range, just document what it is.
You'll also note that in each of the temperature profiles, the test starts at ambient at T0 and shifts to the first controlled test temp at T1. DO-160 includes the following Note as the time to transition from ambient to the test temp will vary:

1) Temperature rate from T0 to T1 is not specified.

You have to remember that DO-160 is about testing extremes. If the equipment can't operate at any point in the ambient range, it's unlikely to operate at the extremes.
BTW, the latest version of DO-160 is rev G.  You should use it for new products.  Using rev D would only be appropriate for re-testing of a product originally developed to DO-160D.


text:
What is the difference between the Bell 412 and the Bell CH-146 Griffon?
What is the difference between the Bell 412 and the Bell CH-146 Griffon?

Have you tried wikipedia?

Fundamentally, the CH-146 is a Bell 412EP, which you can still buy from Bell today.
Some features on the CH-146 you won't find on civilian counterparts:

Weapons.  The CH-146 has attachment points for weapon mounts that aren't typically found on the Bell 412.
Wescam T-16D-A Thermal Imaging System. This wasn't a production addition to the CH-146, but it appears be common on these helicopters.  Similar aftermarket systems might be in use on Bell 412s in police use.
Wire Strike Protection System - some civilian helicopters do have this, but they're particularly common on the CH-146 and other military helicopters.
A Canadian Forces paint job.


text:
Reference Area of Airfoils
Airfoiltools.com shows a higher Lift/Drag coefficient for thick symmetrical foils than for thin symmetrical airfoils.
Is this because the higher drag coefficient of those airfoils is hidden in the reference area/cross-sectional area or is this a true aerodynamic effect that thicker symmetrical foils perform better than thin ones? What is the reference area for airfoils? Is it the cross-section, or the chord length?

When presenting 2D data, all airfoils are non-dimensionalized by the chord (not an area or cross sectional area).
$l=c_l\,q\,c$
Instead of
$L=C_L\,q\,S_\mathrm{ref}$
Used for 3D data.
Note the use of lower-case '$l$' and '$c_l$' which indicate 2D data instead of 3D.
Please post a specific example of an airfoil comparison that raises questions.
For example, here I compare a NACA 0006 (blue) to a 0012 (green) at Re 1e6.
The thinner airfoil has lower drag at zero lift.  However, the thinner airfoil stalls much earlier -- causing the drag increase due to stall to happen much aerlier.
Consequently, the thicker airfoil is able to achieve a much higher L/D at a higher CL.  However, near zero lift, there is a small range where the L/D of the thin airfoil is better than the thick one.
Edit:
You brought the Eppler 473 into the conversation.  So, I created a comparison of that airfoil to the NACA 0012.
Here is the shape comparison.

Not only is the Eppler substantially thicker -- that thickness is located considerably more forward.
That large leading edge radius -- carried back over the airfoil a good distance -- will help to delay stall.  As the airfoil goes to high angle of attack, the leading edge flow is still gentle and relaxed.  Compare to a thin flat plate - or a thin sharp airfoil -- where the flow must accelerate around the corner much more aggressively.
Now, let's compare the performance.

Here we see that below a $c_l$ of about 0.5, the NACA 0012 has notably less drag that the Eppler airfoil.
Interestingly, the two airfoil's stall at about the same angle of attack and lift coefficient.  The difference is that the Eppler airfoil's drag grows more slowly as $c_l$ is increased.  The Eppler foil is able to achieve less form drag with lift than the NACA foil.
The more important fact here is that comparing airfoil maximum L/D is an incomplete measure of airfoil performance.  Without knowing at what lift coefficient it occurs, you don't know what speed or size of wing you will need to utilize that lift coefficient.
These two airfoil's max L/D occurs at about $c_l$ of 0.7 and 0.9.  You need to know that when selecting an airfoil.
You also need to keep track of pitching moment (these are both symmetrical, so they're zero), but if you seek a high-lift, low-drag airfoil, you will likely find one with high moment coefficient.  That will have implications on the size of your tail, etc.
You should create a comparison plot of the Eppler and the Bell 540 at the same Reynolds number and see how they differ.

I enter: maxcamber=0 and sort by lift/drag@RE=1000000. The best foil seems to be eppler 473. With maximum cl/cd=101.
then i reduce the thickness: by entering: maximumthickness=10 and maxcamber=0 and get the BELL 540 AIRFOIL with cl/cd=76.5
so i was wondering why the thick-foil gets better cl/cd.


text:
Is it possible to determine the approximate climb rate of an aircraft knowing its top speed, engine power and weight?
Is it possible to determine the initial climb rate of a craft with a few key pieces of data such as top speed, engine power and weight?
For example the XB-42 was an experimental bomber design from the WW2 era.

Its top speed was 660 km/h at 7,145 meters.
Its empty weight was 9,475 kg and maximum weight was 16,194 Kg.
Its twin engines produced a total of 2,498 kW at takeoff and 2,834 kW using war emergency power.
Is that enough information to determine the approximate climb rate?  Thanks so much for any help!

No, the top speed performance is not enough. To calculate any climb speed one needs to know at which flight speed this climb takes place. Per definition, the climb speed is zero at top speed.
Next, it helps to have some more information about the airframe. The wing's aspect ratio is an important factor because climb happens at lower speed when induced drag is a higher proportion of total drag.
So I need to make two more assumptions in order to find the climb speed:

You want to know the maximum climb speed at sea level.
I am allowed to use information from this answer to complete my knowledge.

Now for the climb speed calculation, which can already be found in several older answers: The flight speed for maximum climb rate is when induced drag is three times as large as zero-lift drag. The first step is to determine the correct polar point. This is a bit more tricky than it sounds because the zero-lift drag coefficient depends on the flight speed and air temperature. Let's start with 0.029 and see where that brings us to:
$$c_{L_{opt.\,climb}} = \sqrt{3\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon} = \text{1.48}$$
That corresponds to a flight speed of
$$v_{opt.\,climb} = \sqrt{\frac{2\cdot m\cdot g}{c_{L_{opt.\,climb}}\cdot\rho\cdot S}} = \text{39.7 m/s}$$
calculated with the MTOW of the XB-42 of 15,060 kg. Now we can determine the ratio of the Reynolds numbers between climb and maximum  speed which is 0.2915. If I assume that the zero-lift drag changes in proportion to $\left(\frac{1}{Re}\right)^{0.2}$, the zero-lift drag at best climb speed rises to 0.02907. Close enough.
However, this speed is rather close to what I suspect is the stall speed of a clean XB-42, and extending flaps will create more drag. Therefore, it will be better to climb at a higher speed, say 50 m/s, and see how fast it climbs there. The zero-lift drag at that speed is scaled to 0.0276 and the lift coefficient to 0.933. Now to the climb speed:
$$v_z = \frac{P_{mot}\cdot\eta_P}{m\cdot g} - \frac{\frac{\rho\cdot v^3}{2}\cdot S\cdot\left(c_{D0}+\frac{c_L^2}{\pi\cdot AR\cdot\epsilon}\right)}{m\cdot g} = \text{12.57 m/s}$$
The symbols used are:
$\kern{5mm} \rho\:\:\:\:\:$ air density = 1.225 kg/m³ at sea level
$\kern{5mm} v\:\:\:\:\:$ flight speed
$\kern{5mm} S\:\:\:\:\:$ wing surface area = 51.6 m²
$\kern{5mm} c_{D0} \:$  zero-lift drag coefficient at 183.3 m/s and 7140 m
$\kern{5mm} c_L \:\:\:$  lift coefficient
$\kern{5mm} \pi \:\:\:\:\:$  3.14159$\dots$
$\kern{5mm} AR \:\:$  aspect ratio of the wing = 8.95
$\kern{5mm} \epsilon \:\:\:\:\:\:$  the wing's Oswald factor = 0.9
$\kern{5mm} m \:\:\:\;$  aircraft mass = 15,080 kg
$\kern{5mm} g \:\:\:\:\;$  gravitational acceleration
$\kern{5mm} P \:\:\:\:\:$  engine shaft power = 2498 kW
$\kern{5mm} \eta_P \:\:\;$  propeller efficiency = 0.85

Thank you so much Peter, I'm going to program this and your other equation with Javscript and produce dozens of different aircraft!  Thanks so much for your knowledge!!!  I'm going to try out a small XB-42 in 1940 with DB601 engines.

+1. Insightful answer!

I would say you can make a pretty good approximation given the data you provided. What is missing is the engine thrust, but maybe you can find it somewhere in the internet, or make an approximation based on that you know that the speed was 660 km/h at 7,145 meters. Drag coefficients do also need to be obtained or guessed.
For sources on how to perform a performance calculation I would use the equations provided in Appendix B in ECAC doc 29, Volume 2.
As a professional you would use the BADA database from Eurocontrol for all performance calculations. Military aircraft is not included in the BADA-database.

Thanks for the equations at the ECAC those are really helpful.  I've got some reading to do!

To answer your question directly - NO, speed, HP, and weight are not enough.
A possible solution is to find weight, hp, and ceiling for it and another aircraft that are very close to each other. The ROC should be similar.
The XB-42 had a Service ceiling of 29,400 ft. You can also use this with the formula given below with a power curve that looks normal by eyeballing.
If you choose to try to calculate ROC, you will have to guess at the power available.

Where:
rc = roc/ft/min
Pa = power available
Pr = power required
W = weight

or

Thanks so much @jwzumwalt!  So in a nutshell the climb rate of an aircraft is a function of POWER/WEIGHT.  As weight increases climb rate decreases.  For WW2 era piston engine aircraft would drag be a significant factor or is POWER/WEIGHT most of the effect?

Yes, but the process will be indirect. For a rough estimate, the engine power- which is the rate at which it can perform work- can be thought of as lifting the mass of the aircraft upwards against gravity. Since the units of power are foot-pounds per second and velocity is in feet per second, the engine power and the aircraft's mass can be used to solve for the climb rate in feet per second (be sure to use the right units for mass). this ignores airframe drag and propeller efficiency losses and as such yields an absolute upper limit for the maximum possible rate of climb. Your mileage will be lower!
Note that engine power depends on density altitude, and hence this estimate holds only for the density altitude at which the engine's power rating was measured & specified.

I know that top speed is largely a function of (power - drag).  So climb rate is largely a function of (power/weight)?

yes. more power + less weight = faster climb.


text:
How many pilots does an airline hire for each new plane they purchase?
I guess this would depend if the airplane is narrow body or wide body because wide body airplanes make longer trips. Another way to ask this question is what is the ratio of airplanes and pilots in an airline company for wide body and narrow body passenger jets respectively.

Pilot is limited, by regulation, to 100 flight hours per month and 1000 flight hours per year, which means average only around 2.7 hours per day. An aircraft may fly maybe 8 (on short routes, so lot of loading and unloading) to over 12 (on long routes) hours a day. And you need two pilots per aircraft.

@JanHudec Good point!  I guess you'd also have to factor in aircraft availability due to maintenance and checks?

@DaveGremlin, I believe those averages are achievable including maintenance.

Related: https://aviation.stackexchange.com/a/25631/679

The answer depends greatly on the airline's operations, as the constraints are very different between long-haul and short-haul trips, whether relief crews are required, layover times, need and distribution of reserve pilots, and other factors: some pilots employed by an airline will be performing management duties, on leave, training, etc.
Assuming the numbers on airlinepilotcentral.com are accurate, we can look at some averages:

Airline
Pilots
Aircraft
Ratio

Emirates
4,300
258
16.7

Delta
14,600
881
16.6

United
12,491
763
16.4

Southwest
9,614
748
12.9

SkyWest
4,621
453
10.2

So I guess this is a major factor in overall operational cost? Seeing as the lower cost (Southwest) and regional (SkyWest) carriers have a lower ratio.

@zymhan We have a past question on that, How much of an airline's costs are labor costs? I think much of the difference comes from the nature of their operations: Southwest and regional airlines tend to fly a lot of short hops with high aircraft utilization, and they never need augmented crews for long flights.

@zymhan Also, pilots are only paid while they’re flying, so the labor cost per hour flown are roughly the same regardless of your ratio.

@StephenS Thanks for the edit. Lovely table!

@StephenS that would depend greatly on the company. At least the ones I know of have a base salary plus extras for flight hours. None that I know of are pure zero hour zero pay -deals.

@ZachLipton Happy to help. It’s a new feature; take a look at the markdown for future reference!

Well, that will depend on variable information sources.
For example: how many pilots are currently working in this company? How many aircraft? Do you have cargo or only passenger aircraft? Is it a single aisle or double aisle aircraft? What is the average flying time per pilot in that company? What is the average flying time for this airline per month?
So I think it is way easier if we took it on bigger scale (worldwide).
Accordingly to statista.com, currently active pilots around the globe are 290,000 pilots, and accordingly to telegraph.co.uk, there are from (23,600 - 39,000) aircraft around the globe. With easy math, you can have an answer of 7.4 pilots per aircraft. But again to answer your question we are going to need to assume some of the parameters are fixed or given! And yeah, I have been told that an A320 aircraft needs 10 pilots on average.

Again from market research into the flight training industry, own work. From beginning 2020 just before the covid slump.

Single aisle passenger aeroplanes require between 3 and 5 crews per plane, so 3-5 FO's and 3-5 captains. Depending on average flight duration, airline growth, local legislation, worldwide job market. So every new additional single aisle aircraft requires an additional 3-5 type rated crews. If the new aeroplane replaces an older type, the existing crews can be type rated for the new type and no additional pilots need to be hired.
Dual aisle, longer range planes require at least double that, up to 12 crews/plane. For the longer flight duration of these aircraft there need to be multiple crews on board, and upon reaching the destination they cannot immediately fly the return flight, they need to rest.